Chivalrous, a.
Etymology: [OF. chevalerus, chevalereus, fr. chevalier. See Chivalry.]
Pertaining to chivalry or knight-errantry; warlike; heroic; gallant; high-spirited; high-minded; magnanimous. In brave pursuit of chivalrous emprise. Spenser.
Shades of meaning
Fernald has no entry of its own for chivalrous; he lists it under brave, generous.
Where he writes about it:
The adventurous man goes in quest of danger; the bold man stands out and faces danger or censure; the brave man combines confidence with resolution in presence of danger; the chivalrous man puts himself in peril for others' protection. — from brave
Courageous is more than brave, adding a moral element: the courageous man steadily encounters perils to which he may be keenly sensitive, at the call of duty; the gallant are brave in a dashing, showy, and splendid way; the valiant not only dare great dangers, but achieve great results; the heroic are nobly daring and dauntless, truly chivalrous, sublimely courageous. — from brave